Drug delivery is the method or process of administering a pharmaceutical compound to achieve a therapeutic effect in humans or animals. Different delivery mechanisms may alter drug release profile, absorption, distribution, and elimination for the benefit of improving product efficacy and safety, as well as patient convenience and compliance. Most common methods of delivery include the preferred non-invasive peroral (through the mouth), topical (skin), transmucosal (nasal, buccal/sublingual, vaginal, ocular and rectal), and inhalation routes. Injection or infusion is used to deliver medications such as peptides, proteins, antibodies, vaccines, and gene based drugs because such medications are generally susceptible to enzymatic degradation or are unable to be absorbed into the systemic circulation efficiently due to their molecular size and charge for therapeutic efficacy. For example, many immunizations are based on the delivery of protein drugs and are often done by injection.
Targeted drug delivery or targeted delivery is one of the areas in drug delivery that has drawn immense attention. The basic concept is to develop delivery mechanisms that cause the drug to be active only in a particular target area of the body (for example, in cancerous tissues). Sustained release formulation is another area in which the drug is released over a period of time in a controlled manner from a formulation. Sustained release formulations often include the use of liposomes, biodegradable microspheres, and drug-polymer conjugates.
Drug delivery remains one of the most complex, intriguing, and exciting research areas in industry, medicine, science, and technology. Therefore there is an ongoing need and interest to develop new methods and systems to improve drug delivery in various aspects.